Circumsporozoite (CS) proteins, which densely coat malaria (Plasmodia) sporozoites, contain an amino acid sequence that is homologous to segments in other proteins which bind specifically to sulfated glycoconjugates. The presence of this homology suggests that sporozoites and CS proteins may also bind sulfated glycoconjugates. This hypothesis was tested and results indicate that CS proteins and sporozoites bind specifically to certain sulfated glycoconjugates. Naturally occurring oligosaccharides, even if isolated from a single protein glycosylation site, can present a daunting array of structures for the glycobiologist to analyze. The molecular details of how glycoconjugate-binding proteins interact with their ligands have been revealed by a variety of techniques.The molecular details of how glycoconjugate-binding proteins interact with their ligands have been revealed by a variety of techniques. For example, proteases, chemical modifying reagents, and antibodies have served as effective probes of lectin functional domains. Highly focused regions of sequence homology has indicated that many structures within the lectin glycoconjugate-binding domains themselves may be conserved. Mannose-binding protein (MBP)1 binds with high affinity to glycoconjugates containing terminal mannose or N-acetylglucosamine residues, and binds more weakly to those containing terminal fucose residues Mannose-binding protein was purified from human serum to apparent homogeneity by affinity chromatography on mannose-Sepharose, followed by affinity chromatography on underivatized Sepharose. Approximately 0.4 mg protein was obtained from 1 liter serum. The glycosphingolipid binding specificity of the purified protein was examined by chromatogram overlay and solid phase assays. The binding specificity was described.